To provide markers for airport runways and taxiways, it has become customary to employ light fixtures along the edges of runways and taxiways to facilitate guidance of aircraft during take-off, landing and taxiing operations. Conventional runway and taxiway elevated edge light fixtures typically consist of an upright support member or pedestal with a lamp assembly and prismatic globe mounted at its upper end. The support member is threadably or otherwise evgageable at its lower end with a base plate permanently mounted in or adjacent to the runway or taxiway. The globe provides a protective cover for the lamp assembly and can be optically configured as a lens to transmit light in a predetermined direction.
Such airport light fixtures are subjected to severe vibrations and high wind velocity, especially during aircraft operations. To preserve the desired directional alignment of these light fixtures, it is imperative that such fixtures be able to withstand such vibrations adn wind velocity without becoming tilted, misaligned or otherwise out of adjustment. However, for convenience and efficiency in the initial installation of such light fixtures and the subsequent correction of any misalignment which may occur, such fixtures should be readily adjustable externally while in place and without disassembly. To provide increased flexibility in leveling, such fixtures should be adjustably tiltable to plus or minus 7 degrees from horizontal at any point on a 360 degree horizontal plane. Moreover, such light fixtures should be provided with an optical globe which is firmly secured but conveniently removable for facilitating repair and/or replacement of the lamp, the lamp assembly, and the globe, as necessary.
As mentioned, precise angular orientation of the globe, i.e. position accuracy, is essential in such airport light fixtures. This is particularly so in bidirectional applications, in which horizontal aiming is critical. Convenience and efficiency in installation, repair and replacement of the globe may, thus, not be achieved at any sacrifice to position accuracy.
In order to provide the precise light pattern required, it is important that the lamp assembly of the light fixture be accurately and rigidly located. In the airport light fixture disclosed, for example, in U.S. Pat. No. 4,104,711, such precise location of the lamp assembly is achieved by mounting the electric lamp in an electrical socket which is supported by a mounting bracket which, in turn, is rigidly secured to the lamp base. Typically, such electrical sockets are secured by conventional nut and bolt type assembly hardware which is time-consuming to assemble and/or disassemble.
An additional problem arises from the fact that the design of electrical socket mounting brackets in conventional airport light fixtures has not adequately taken into account the applicable thermal considerations, and in particular, the need to minimize heat absorption by the bracket and heat transfer to the bracket.
An airport light fixture for mounting on a substantially cylindrical support column, comprising a lamp structure for providing illumination; an optical globe for covering the lamp and for directing the light emanating therefrom; and a base member for securely mounting the globe and the lamp structure in an adjustable, substantially upright position on the support column, the globe being releasably securable to the base member and substantially sealed over the lamp structure for protecting the lamp structure, the base member including, at its bottom, a mounting hub for mounting the base member on the upper end of the support column, the mounting hub including: (a) a substantially annular planar support surface positioned on the upper end of the support column when the base member is mounted thereon; (b) a substantially cylindrical collar depending downwardly from the planar support surface and having a plurality of leveling screws extending transversely therethrough for contacting the peripheral surface of the support column when the base member is mounted thereon for adjusting the tilt of the base member, as necessary, to obtain and securely maintain the desired vertical positioning of the globe; and (c) a plurality of guide ribs depending downwardly from the planar support surface and interiorly of the collar, the guide ribs being spaced around the support surface, and the interior surface of each of the ribs facing the support column when the base member is mounted thereon being equivalently tapered such that an imaginary surface passing through each of the individual surfaces is frustro-conically shaped and has its smaller diameter end adjacent the planar support surface, the smaller diameter being substantially equal to the outer diameter of the upper end of the support column for guiding the planar support surface of the mounting hub to the desired position above such upper end during mounting of the base member on the support column; the taper and positioning of each of the guide ribs, and the positioning of the collar and the leveling screws, being selected to permit adjustment of the tilt of the support member at any point on the circumference of the support column, as necessary to obtain the desired vertical positioning of the globe.
Additionally, a lamp socket mounting bracket comprising a pair of rigid, substantially upright, spaced apart support legs, each of the legs being secured at its bottom to the top portion of the base member in substantially parallel relationship at opposite sides thereof, each of the legs having at least two substantially upright stops projecting laterally therefrom in parallel relationship, the upper ends of each pair of stops being adjoined by a cross piece which forms a shelf for supporting the socket, the mounting bracket further having two, parallel, spaced apart retainer flanges connecting the upper ends of the legs and extending substantially orthogonally thereto for contacting the upper surface and the respective side surfaces of the socket when the socket is supported on the shelves for substantially preventing upward and lateral movement of the socket, respectively, each of the stops on one of the legs having an elongated surface inclined inwardly from the bottom, and the stops on the other of the legs each having similarly inclined elongated surfaces, the legs and the stops being situated such that, during upward insertion of the socket into the mounting bracket from below, the socket operatively engages the inclined surface of each of the stops, causing the legs to flex outwardly away from one another for permitting the socket to pass upwardly along and then beyond the inclined surfaces, the legs, the retainer flanges, and the junction therebetween being adapted to permit the legs to resiliently return to substantially their original positions, with the socket then resting on the shelves.
Also, a base member for mounting a globe and lamp assembly of an airport light fixture on a support column, including at least one resilient finger-like member having its free end normally extending upwardly a preselected distance above the globe support surface for engaging at least one of the globe tongues to deter or retard rotation of the globe on the base member in a rotational direction opposite to the one direction, the free end being displacable towards the globe support surface when the finger-like member is resiliently flexed downwardly for permitting desired rotation of the globe in such opposite direction.